The present invention relates generally to medical and surgical devices and methods thereof. Specifically, the present invention relates to an intravascular hemostasis device and method used to create a blood-free area in a portion of a blood vessel, such as the aorta, or a body organ, during a medical or surgical procedure, such as a proximal anastomosis procedure, while still permitting the flow of blood within the vessel.
A manifestation of coronary artery disease is the build-up of plaque on the inner walls of the coronary arteries, which causes narrowing or complete closure of these arteries, resulting in insufficient blood flow. This deprives the heart muscle of oxygen and nutrients, leading to ischemia, possible myocardial infarction and even death. Surgery to alleviate this problem often involves creating an anastomosis between a coronary artery and a graft vessel to restore a blood flow path to essential tissues. An anastomosis is a surgical procedure by which two vascular structures, such as a graft vessel and a coronary artery, are interconnected.
Conventional coronary bypass graft procedures require that a source of arterial blood be prepared for subsequent bypass connection to the diseased artery. An arterial graft can be used to provide a source of blood flow, or a free vessel graft may be used and connected at the proximal end to a source of blood flow. Preferably, the source of blood flow is any one of a number of existing arteries that are dissected in preparation for the bypass graft procedure. In many instances, it is preferred to use either the left or right internal mammary artery. In multiple bypass procedures, it may be necessary to use free vein graft vessels such as the saphenous vein of the leg or the cephalic or basilic veins in the arm. Alternatively, free arterial grafts can be used when the leg or arm veins are unavailable or are unsuitable, such as the gastroepiploic artery in the abdomen, and other arteries harvested from the patient""s body. Synthetic graft materials, such as Dacron or Gortex grafts, can be used as well. If a free graft vessel is used, the upstream end (proximal) of the dissected vessel, which is the arterial blood source, will be secured to the aorta to provide the desired bypass blood flow in a proximal anastomosis procedure, and the downstream end (distal) of the dissected vessel will be connected to the target vessel in a distal anastomosis procedure.
Currently, the conventional practice in performing coronary artery bypass graft surgical procedures is to open the chest by making a longitudinal incision along the sternum (e.g., a partial or median sternotomy), placing the patient on a cardiopulmonary bypass (CPB) (heart-lung) machine, stopping the heart from beating by administering a conventional cardioplegia solution (e.g., a potassium chloride solution) to the heart, and then attaching the coronary artery bypass graft(s) to the coronary arteries (and/or aorta in the case of the proximal end of a free graft vessel). The heart-lung machine is needed to maintain the blood circulation through the patient and to provide gas and heat exchange surfaces. However, there are numerous complications associated with conventional open-chest procedures, many of which are related to the use of a heart-lung machine. The use of a heart-lung machine has been shown to be the cause of many of the complications that have been reported in conventional coronary artery bypass graft procedures, such as complement and neutrophil activation, adverse neuropsychologic effects, coagulopathy, and even stroke. The period of CPB should be minimized, if not avoided altogether, to reduce patient morbidity.
A current trend in coronary artery bypass graft surgery is to utilize a minimally invasive surgical technique. Minimally invasive techniques (i.e., surgical techniques that avoid the partial or median sternotomy and/or the use of CPB) have been developed to attempt to reduce or eliminate some of the more serious complications of conventional open-chest cardiac surgery techniques, such as the morbidity associated with the use of CPB. One approach to minimally invasive cardiac surgery is an endoscopic procedure in which access to the heart is gained through several small openings, or ports, in the chest wall of a patient. The endoscopic method allows surgeons to stop the heart without cracking the chest by utilizing a series of internal catheters to stop blood flow through the aorta and to administer a conventional cardioplegia solution (e.g., a potassium chloride solution) to facilitate stopping the heart. The cardioplegia solution paralyzes the electrical activity of the heart and renders the heart substantially totally motionless during the surgery. The endoscopic approach utilizes groin cannulation to establish CPB which takes over the function of the heart and lungs by circulating oxygenated blood throughout the body. After CPB is started, an intraaortic balloon catheter that functions as an internal aortic clamp by means of an expandable balloon at its distal end is used to occlude blood flow in the ascending aorta from within. A full description of an example of one preferred endoscopic technique is found in U. S. Pat. No. 5,452,733, the complete disclosure of which is incorporated by reference herein. A primary drawback of endoscopic cardiac surgery procedures, however, is that such procedures do not avoid the damaging effects of CPB generally described above.
An approach to minimally invasive cardiac surgery that avoids CPB and aortic cross-clamping is minimally invasive direct coronary artery bypass grafting (MIDCAB) on a beating heart. Using this method, the heart typically is accessed through a minithoracotomy (i.e., a 6 to 8 cm incision in the patient""s chest) which also avoids the sternal splitting incision of conventional cardiac surgery. The heart may also be accessed through a partial or median sternotomy in an off-pump coronary artery bypass graft (OPCAB) technique which gives the surgeon greater direct acces to the heart. In both the MIDCAB and OPCAB procedures, the anastomosis procedure is then performed under direct vision on the beating heart without the use of CPB or potassium chloride cardioplegia. However, there are many obstacles to precise coronary anastomosis during MIDCAB or OPCAB on a beating heart. In particular, the constant translational motion of the heart and bleeding from the opening in the coronary artery hinder precise suture placement in the often tiny coronary vessel.
In response to problems associated with the above-described minimally invasive surgical techniques, a new minimally invasive surgical platform known as the Transarrest(trademark) platform has been developed to minimize the cardiac motion of the beating heart while avoiding the need for CPB, aortic cross-clamping and conventional cardioplegia. The Transarrest(trademark) platform employs a novel pharmaceutical approach to stabilizing the heart. This revolutionary pharmaceutical approach to cardiac stabilization is fully described in co-pending patent application for xe2x80x9cCompositions, Apparatus and Methods For Facilitating Surgical Procedures,xe2x80x9d Ser. No. 09/131,075, filed Aug. 7, 1998 and invented by Francis G. Duhaylongsod, M.D, the entire contents of which are expressly incorporated by reference herein. As described therein, pharmaceutical compositions, devices, and methods are provided which are useful for medical and surgical procedures which require precise control of cardiac contraction, such as minimally invasive coronary bypass procedures. Generally, the Transarrest(trademark) platform involves the administration of a novel cardioplegia solution which provides for precise heart rate and rhythm control management while maintaining the ability of the heart to be electrically paced (i.e., which does not paralyze the electrical activity of the heart as with conventional cardioplegia solutions). Specifically, the novel cardioplegia solution comprises a pharmaceutical composition which is capable of inducing reversible ventricular asystole in the heart of a patient, while maintaining the ability of the heart to be electrically paced. xe2x80x9cReversible ventricular asystolexe2x80x9d refers to a state wherein autonomous electrical conduction and escape rhythms in the ventricle are suppressed. A state of the heart may be induced wherein the heart is temporarily slowed to at least about 25 beats per minute or less, and often about 12 beats per minute or less. The induced ventricular asystole is reversible and after reversal, the heart functions are restored, and the heart is capable of continuing autonomous function.
The pharmaceutical composition may preferably include, for example, an atrioventricular (xe2x80x9cAVxe2x80x9d) node blocker and a beta blocker. As used herein, the term xe2x80x9cAV node blockerxe2x80x9d refers to a compound capable of reversibly suppressing autonomous electrical conduction at the AV node, while still allowing the heart to be electrically paced to maintain cardiac output. Preferably, the AV node blocker, or the composition comprising the AV node blocker, reduces or blocks ventricular escape beats and cardiac impulse transmission at the AV node of the heart, while the effect on depolarization of the pacemaker cells of the heart is minimal or nonexistent. The beta blocker is provided in one embodiment in an amount sufficient to substantially reduce the amount of AV node blocker required to induce ventricular asystole. For example, the AV node blocker may be present in the composition in an amount which is 50% or less by weight, or optionally about 1 to 20% by weight of the amount of AV node blocker alone required to induce ventricular asystole.
The pharmaceutical composition, such as an AV node blocker, capable of causing ventricular asystole in a preferred embodiment is a cholingeric agent such as carbachol, although other cholingeric agents may be used as well such as acetylcholine, methacholine, bethanechol, arecoline, norarecoline, neostigmine, pyridostigmine, and other agents that increase cyclic GMP levels by direct or indirect cholinergic receptor stimulation. Other exemplary AV node blockers include calcium channel blockers, adenosine Al receptor agonists, adenosine deaminase inhibitors, cholinesterase inhibitors, monamine oxidase inhibitors, serotoninergic agonists, antiarrythmics, cardiac glycosides, and local anesthetics. Examples of these AV node blockers include verapamil, diltiazem, lidocaine, procaine, procainamide, quinidine, choloroquine, amiodarone, pilocarpine, ethmozine, propafenone, flecainide, encainide, tranylcypromine, serotonin, adenosine, digoxin, digitalis, dipyridamole, ibutilide, zapranest, sotalol, metoclopromide and combinations thereof.
In the preferred embodiment, the beta blocker is propranolol, although other suitable beta blockers may be used as well. Other exemplary beta blockers include atenolol, acebutolol, labetalol, metoprolol, nadolol, oxprenolol, penbutolol, pindolol, sotalol and timolol, and any combinations or pharmaceutically acceptable salts thereof. Alternatively, celiprolol, betaxolol, bevantolol, bisoprolol, esmololol, alprenolol, carterolol, nadolol, or teratolol may be used. The beta blocker may be any naturally occurring or synthetic analogue capable of blocking beta-adrenergic receptor sites. The administration of the beta blocker is preferably prior to, or contemporaneously with, the administration of the cholinergic agent, and results in a synergistic effect between the beta blocker and the cholinergic agent. The use of a cholinergic agent, such as carbachol, in combination with a beta-blocker, such as propranolol, produces ventricular asystole at significantly reduced dosages compared to the cholinergic agent used alone, while maintaining a short half-life and rapid onset of effect.
In one embodiment to induce reversible ventricular asystole in a patient, the beta-blocker propranolol and the AV node blocker carbachol are serially administered in an initial intracoronary bolus to the right or left coronary artery to induce reversible ventricular asystole of the heart, and then carbachol is administered as a periodic (e.g. one or more bolus infusions) or continuous intracoronary infusion to maintain ventricular asystole during the course of the surgical procedure. For example, an intracoronary injection of about 0.5 to 4 mg, for example about 1 mg, of propranolol is administered by intracoronary infusion over a time period of about 0.5 to 3.0 minutes, e.g., about 1 minute, preferably followed by a saline flush, such as 2 mL saline flush. This is followed by an intracoronary bolus injection of about 0.01 to 0.5 mg, e.g., about 0.025 to 0.3 mg, e.g., about 0.1 mg carbachol administered over about 0.5 to 3.0 minutes, e.g., about 1 minute, to initially induce ventricular asystole. To maintain ventricular asystole, carbachol is administered as one or more bolus administrations (e.g., about 0.05 mg/bolus) or as an intracoronary infusion to the right or left coronary artery at a rate of about 0.01 to 0.3 mg/min, e.g., about 0.025 to 0.3 mg/min, for example, about 0.01 to 0.1 mg/min, e.g., about 0.05 to 0.1 mg/min, e.g., about 0.0825 mg/min, for a time period of about 5 to 90 minutes, preferably about 30 to 90 minutes, depending on the length of the procedure. A dosage amount of about 1.0 mg of phenylephrine may be administered to control the hypotensive effects associated with carbachol administration. Atropine (about 1 mg) may be used to reverse ventricular asystole and restore the heart to its normal function.
Electrical pacing wires are connected to the right ventricle and/or left ventricle and/or atria and are used to pace the heart using a novel foot-actuated pacer control system to maintain the patient""s blood circulation during the periods in which the surgeon is temporarily not performing the surgical procedure. Thus, for example, in a coronary bypass procedure, the surgeon can control the pacing of the heart with a convenient foot pedal and can controllably stop the heart as sutures are placed in the vessel walls. The pharmaceutical compositions, devices and methods for drug delivery, and systems for pacing the heart, give a surgeon complete control of the beating heart. The Transarrest(trademark) procedure described above can be used to facilitate any surgical procedure which requires intermittent stoppage of the heart or elimination of movements caused by pulsatile blood flow, whether access is gained to the body cavity via a partial or median stemotomy incision, via a mini-thoracotomy incision, or via one or more small incisions or ports in the chest wall.
In performing a coronary bypass graft procedure to the aorta using the Transarrest(trademark) procedure described above (or any of the other open-chest or minimally invasive approaches to cardiac surgery described above), it is necessary to create a hole in the aorta where a proximal anastomosis graft is to be made. To prevent blood loss through this hole, typically the aorta is clamped with a conventional U-shaped xe2x80x9cside-bitingxe2x80x9d clamp to temporarily stop or substantially minimize the blood flow through the aorta. Another surgical technique involves the use of the aortic cross-clamp which is employed when conventional cardioplegia is administered. A problem with these techniques is that the compressive forces of the clamp increase the risk that plaque or other atherosclerotic material accumulated on the walls of the aorta will be released into the blood stream, which can lead to embolic events such as myocardial infarction or cerebral deficits such as stroke.
Thus, it would be desirable to provide an anastomosis assist device, preferably of relatively simple construction and cost, which is designed to eliminate clamping during a proximal anastomosis procedure in which a free graft vessel is grafted to the aorta. Examples of previous attempts to reduce the risks of a proximal anastomosis procedure by avoiding the untoward effects of aortic clamping are provided in PCT Patent Application WO 97/40881 to Jonkman et al., PCT Patent Application No. WO 98/52475 to Nobles et al., and European Patent Application No. EP 0895753 to Borst et al., the entire contents of which are expressly incorporated by reference herein. The present invention involves improvements to devices and methods for sealing an opening in a blood vessel, such as in the aorta where an anastomosis graft is to be made, while still permitting the flow of blood through the blood vessel.
The present invention involves several embodimients of an intravascular hemostasis device and method which are adapted to seal an opening in a blood vessel, such as an aorta, while still permitting blood flow through the vessel. The present invention is particularly well-suited to facilitate a proximal anastomosis procedure in which a free end of a graft vessel, such as a saphenous vein, is secured to an opening in a side wall of the aorta. However, those of ordinary skill in the art will recognize that the present invention can be used in any medical or surgical procedure in which it is necessary to form a seal against a wall of a blood vessel or other body organ.
According to a first aspect of the present invention, an intravascular hemo stasis device is disclosed which generally comprises at least a first elongated tubular member having a proximal end portion and a distal end portion, and a flexible, deformnable sealing member coupled to the distal end portion of the elongated tubular member which has at least a first pre-formed expanded state, the sealing member being at least partially radially compressible to at least a first compressed state for insertion of the sealing member into an opening in a blood vessel, the sealing member being radially selfexpandable from its compressed state to its expanded state after the sealing member is inserted into the opening in the vessel in which the sealing member is adapted to substantially seal against an inner wall of the blood vessel around the opening. Advantageously, the sealing member has a pre-formed cup-shaped configuration in its first expanded state in which the sealing member has a circumferential rim portion which is adapted to form a seal against the inner wall of the blood vessel around the opening.
In a preferred embodiment, the sealing member is moveable to an inverted configuration to facilitate its removal from the blood vessel in which the sealing member has a second expanded state which is a mirror image of its first expanded state when a sufficient force is applied to the sealing member. For example, the sealing member is configured such that when a sufficient force is applied to the sealing member by the inner wall of the blood vessel as the elongated tubular member is moved away (e.g., proximally) from the blood vessel, the sealing member will invert to its inverted configuration. The sealing member is at least partially radially compressible from its second expanded state to a second compressed state to allow for removal of the sealing member from the blood vessel through the opening in the blood vessel.
Advantageously, the intravascular hemostasis device in a preferred embodiment also includes a support element coupled to or immediately adjacent the sealing member to provide enhanced rigidity to the sealing member when in its expanded state to prevent the sealing member from inadvertently inverting to its inverted configuration during use of the device and to provide enhanced rigidity to the sealing member to enhance its sealing function. For example, in one embodiment, the intravascular hemostasis device includes a support hub located adjacent to the sealing member and a second elongated tubular member slidably coupled to the first elongated tubular member, with the support hub being coupled to a distal end portion of the second elongated tubular member. The support hub is spring-biased in its natural configuration to engage a distal shoulder portion of the sealing member to provide enhanced support and rigidity thereto. An actuator is operatively coupled to the second elongated tubular member. The support hub is moveable axially relative to the sealing member upon actuation of the actuator which facilitates inversion and removal of the sealing member from the blood vessel through the opening in the wall of the blood vessel.
In an alternative embodiment, the support element comprises a plurality of wires movably embedded within the sealing member which provide support to the sealing member in its expanded state. An actuator is operatively coupled to the plurality of wires and is operable to withdraw the plurality of wires externally from the sealing member to facilitate inversion and removal of the sealing member from the blood vessel through the opening in the wall of the blood vessel. The sealing member may also include retaining means for retaining the sealing member in abutting engagement with an interior wall of the blood vessel to allow for substantially hands-free operation of the device. The retaining means, can include, among other things, a suction force which is applied to the sealing member to retain the sealing member in abutting engagement with the interior wall of the vessel around the opening therein. Other types of retaining means are further disclosed below.
According to a further aspect of the present invention, an intravascular hemostasis device is disclosed which generally comprises a first elongated tubular member, a second elongated tubular member rotatably coupled to the first elongated tubular member, a flexible sealing member coupled to distal end portions of the first and second elongated tubular members, the sealing member being moveable between a narrow, collapsed configuration in which the sealing member is adapted to be inserted into and removed from a blood vessel through an opening in a wall of the blood vessel, and an expanded configuration in which the sealing member is adapted to form a seal against an inner wall of the blood vessel around the opening, and wherein the sealing member is selectively adjustable between its narrow, collapsed configuration and its expanded configuration upon relative rotational movement of the first and second elongated tubular members from outside the blood vessel. The sealing member can comprise a wire or ribbon which is spiralled about the distal end portions of the first and second elongated tubular members. The wire or ribbon is at least partially coated with a polyurethane material to make it impermeable to fluid flow. An actuator is coupled to a proximal end portion of the second elongated tubular member and is operable to rotate the second elongated tubular member relative to the first elongated tubular member to selectively move the spiralled wire or ribbon between its narrow, collapsed configuration and its expanded configuration in which the wire or ribbon assumes a general cup-shaped configuration which is adapted to seal against the opening in the wall of the vessel.
In yet another alternative embodiment of the invention, an intravascular hemostasis device is disclosed which generally comprises a first elongated tubular member, a second elongated tubular member movably coupled to the first elongated tubular member, a flexible sealing member coupled to a distal end portion of the second elongated tubular member, the sealing member being moveable between a narrow, collapsed configuration in which the sealing member is adapted to be inserted into and removed from a blood vessel through an opening in a wall of the blood vessel, and an expanded configuration in which the sealing member is adapted to form a seal against an inner wall of the blood vessel around the opening, and wherein the sealing member is selectively adjustable between its narrow, collapsed configuration and its expanded configuration upon relative axial movement of the first and second elongated tubular members from outside the blood vessel. The sealing member may comprise a plurality of spaced-apart wire loops that are coated with a polyurethane material to form an impermeable barrier to fluid flow. The plurality of wire loops are preformed to assume an expanded configuration when extending from the first elongated tubular member, and can be withdrawn into the first elongated tubular member to assume a collapsed configuration upon actuation of the second elongated tubular member.
According to another aspect of the present invention, several methods of performing a coronary bypass procedure are disclosed which in one embodiment generally comprises providing a graft vessel having a first free end and a second free end; providing an intravascular hemostasis device comprising an elongated tubular member having a proximal end portion, a distal end portion, and a flexible, deformable sealing member coupled to the elongated tubular body adjacent the distal end portion, the sealing member being adapted for relative movement between a natural pre-formed first expanded state and a compressed state; forming an opening in a side wall of an aorta; inserting the distal end of the elongated tubular body and the sealing member into the aorta through the opening while the sealing member is in its expanded state such that the side wall of the aorta around the opening exerts an inwardly directed force over at least a portion of the sealing member to cause it to move from its expanded state to its compressed state; moving the elongated tubular body proximally away from the aorta following radial expansion of the sealing member into its expanded state within the aorta until the sealing member in its expanded state contacts the interior of the side wall of the aorta and substantially seals the opening from blood flowing through the aorta; at least partially attaching the first free end of the graft vessel to the side wall of the aorta about the opening; and removing the intravascular hemostasis device from the aorta. Other methods for sealing an opening in a blood vessel or body organ are described in detail below and in the appended claims.
The invention described below solves the deficiencies of the prior art and offers a number of other features and advantages that will be apparent to one of ordinary skill in the art from the following detailed description, accompanying figures and appended claims.